The present invention relates to a power connection apparatus for supplying a power to, for example, an illuminative lamp or the like in a showcase.
In general, a showcase or the like is provided with a power connection apparatus constituted of a power socket connected into a chamber of a main body and a power plug plugged in this power socket to supply a power to an illuminative lamp or the like. In a conventional power connection apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 11-273775 (the patent document), a power socket is provided with a recess portion in which an electrode portion is disposed. This electrode portion is provided with plug-in ports for a power source. A power plug comprises a main body and a cylindrical portion connected to an illuminative lamp or the like via a wiring line, and terminals are provided on a bottom portion inside the cylindrical portion. In consequence, the power plug is plugged in the electrode portion of the power socket by plugging the terminals of the power plug in the power source plug-in ports of the power socket.
When the power connection apparatus is used in a low temperature showcase, the power plug serves for each of illuminative lamps and the like provided under front ends of a plurality of shelf devices arranged in the chamber. In a case where the layout or the like of the chamber is changed, the arrangement positions of the shelf devices are changed. Accordingly, the power socket to be connected to the power plug is also changed.
On the other hand, when the power connection apparatus is provided on an back surface in the chamber which becomes a low temperature in the showcase, humidity generated in the chamber easily invades each connecting portion between the electrode portion and the terminal. The invasion of the humidity causes electrical leakage or incurs the rusting of the terminals and the like. Moreover, frost is generated between the power plug and the power socket, which causes a problem that with the growth of the frost, a force is applied in a direction in which the power plug is detached from the power socket, and the power plug drops down.
To solve the problem, a preventive structure is employed in the connecting portion between the power plug and the power socket. However, this obstructs the attachment/detachment operation of the power plug and the power socket. Furthermore, in a low temperature environment, air in the power socket contracts, and accordingly, the attachment/detachment operation further becomes difficult.
Therefore, to secure the connection between the power plug and the power socket, there has heretofore been developed a constitution in which engagement portions are provided on a power socket side, a handle rotatable at one end thereof is provided on a power plug side, and the handle has the other end provided with engaging claws disengageably engaged with the engagement portions on the power socket side.
In the above conventional constitution, when the power plug is connected to the power socket, the terminals of the power plug are pushed into power source portions of the power socket in a state where the handle is raised, whereby the engaging claws formed at the end of the handle are engaged with the engagement portions on the power socket side owing to the elastic force of the claws. However, the power socket attached in the showcase is usually provided on the back surface in the chamber, and hence an operator performs an operation of pushing the power plug into the power socket provided on the back surface in the chamber from the front side of the showcase. In this case, the operator is distant from the back surface in the chamber to a considerable degree, and hence to facilitate the operation, it is required that the power plug is pushed into the power socket in a state where the handle of the power plug is brought down to the front side, and then the handle is upwardly rotated to engage the engaging claws of the power plug with the engagement portions of the power socket.
Moreover, in the constitution, the handle can further rotate downwardly from substantially right angles with respect to the power socket, and hence when the end of the handle on the power socket side abuts on the power socket in a state where the handle is rotated downwardly on the front side owing to the own weight thereof, the abutment portion disturbs and disenables the operation of rotating the handle upwardly. In consequence, after once rotating the handle upwardly, the power plug has to be inserted into the power socket while keeping the position of the handle, and a problem occurs that connecting operation properties become complicated.
The present invention has been developed to solve the conventional technical problem, and an object thereof is to provide a power connection apparatus which can secure connection between a power socket and a power plug and which can simplify the connecting operation properties thereof.